Larry, Lionel, and Lester painted a fence. Larry painted the first 1/3 of the fence. Lionel painted 3/5 of what rtemained. Lester painted the final 40 ft. How long is the fence?

fence length x

after Larry (2/3) x left to paint
after Lionel (2/5)(2/3)x left to paint
so
40 = (4/15) x